The present invention relates to satellite borne radiometers and, more particularly, to a radiometer incorporating a cylindrical parabolic antenna and a minimum redundancy array feed adapted for use on satellites for remote radiometric imaging or mapping.
A radiometer is a well-known device which senses and measures radiant energy. Selection of sensors adapts the radiometer to sense radiation in specific frequency bands, such as infrared and radio frequency bands, for example. Satellite borne radiometers are used for both terrestrial and extraterrestrial mapping. Typically, the satellite traverses an orbit that tracks a specific path that has the area to be mapped. This is accomplished by establishing a specific orbital track or by the relative motion of the satellite to ground. Typically, prior art radiometers scan a single pencil-beam footprint along a conical path by means of a rotating parabolic reflector. Such a radiometer is disclosed in U.S. Pat. No. 4,724,439 to Wiley et. al. Such radiometers, while successful, require the use of a mechanical scanning mechanism, such as a rotating reflector to accomplish the conical scan, thereby adding to the size, weight, and physical complexity of the system. Scanning of the pencil-beam further reduces the available time for integration of the sensed radiation thereby limiting system sensitivity. Accordingly, there has existed a need for an improved radiometer that eliminates the need for complex mechanical systems and increases sensed signal integration time.